It does seem rather astonishing that they don't test these devices. It's not only fraud you need to rule out, but also genuine manufacturing errors, equipment w

It does seem rather astonishing that they don't test these devices. It's not only fraud you need to rule out, but also genuine manufacturing errors, equipment wear and tear, etc. The only explanation I could understand is that these were deliberate false positive machines (either for illegitimate profiling or parallel construction), but that doesn't seem to be how they functioned.